Vibration isolation unit

ABSTRACT

To provide a vibration isolation unit capable of reducing the number of parts, man-hour and material cost, and suppressing the product cost. One side of a stopper rubber member continues to the outer edge of a diaphragm. Accordingly, because they can be vulcanizingly molded simultaneously, the number of parts can be reduced. Also, because the diaphragm is attached to an outer tube member, the stopper rubber member also can be fixed simultaneously, and therefore the man-hour can be reduced. Further, because one side of the stopper rubber member continues to the outer edge of the diaphragm, overlapping of them in an axial view can be avoided, and a rubber material can be used efficiently. Thus, the number of parts, man-hour and material cost can be reduced and the product cost of the overall vibration isolation unit can be suppressed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vibration isolation unit, and relatesspecifically to a vibration isolation unit that can reduce the number ofparts, man-hour and material cost, and can thereby suppress the productcost.

2. Description of the Related Art

As a vibration isolation unit preventing vibration of an engine for anautomobile from being transmitted to a vehicle body while supporting andfixing the engine, one provided with a liquid-sealed vibration isolationdevice is known. In the vibration isolation unit, the liquid-sealedvibration isolation device is interposed between the engine and thevehicle body through an engine side bracket and a vehicle body sidebracket.

For example, in Japanese Unexamined Patent Application Publication No.2009-14080 (refer to FIG. 1 to FIG. 3, FIG. 14 to FIG. 16, paragraphs0029, 0036 to 0038, and the like), an inverted type vibration isolationunit is disclosed in which a vibration isolation body 18 (liquid-sealedvibration isolation device) is configured such that a lower attachingtool 12 is attached to the vehicle body side through a frame-like secondbracket 22 (vehicle body side bracket) of a rectangular shape in a frontview and an upper attaching tool 14 is attached to the engine sidethrough a first bracket 20 (engine side bracket) projecting sideways, inthe vibration isolation body 18, the lower attaching tool 12 (bossmember) and the upper attaching tool 14 (outer tube tubular part) areconnected by a vibration isolation base body 16, and a liquid-sealedchamber 28 is formed between the isolation base body 16 and a diaphragm30.

In the vibration isolation unit, as a stopper mechanism damping andrestricting excessive relative displacement of the upper attaching tool14 with respect to the lower attaching tool 12, a stopper rubber 84 isfurnished in the first bracket 20. The stopper rubber 84 includes afirst stopper rubber 86 arranged so as to cover the upper surface of thevibration isolation body 18 and opposing an upper wall 76 of the secondbracket 22, and a second stopper rubber 88 extended downward from anedge of the first stopper rubber 86 and interposed between a tubularholding part 46 (pressed-in part) of the first bracket 20 and a verticalwall 74 (side wall) of the second bracket 22.

Also, at the lower end of the second stopper rubber 88, a fixing rubberpiece 96 is extended inward in the radial direction, and the stopperrubber 84 is fixed without dropping and dislocation because the fixingrubber piece 96 is held between a flange 26 of the upper attaching tool14 and a lower end 46c of the tubular holding part 46 of the firstbracket 20.

However, the number of parts increases because the conventionalvibration isolation unit described above is configured such that thestopper rubber 84 is vulcanizingly molded as a single body and ismounted so as to cover the first bracket 20. Also, in the manufacturingprocess of the vibration isolation unit, it is required to control toconfirm that the fixing rubber piece 96 is properly held between theflange 26 and the tubular holding part 46, and therefore the man-hourincreases. Further, rubber material is used inefficiently because a partof the first stopper rubber 86 covering the upper surface of thevibration isolation device body 18 overlaps with a part of the diaphragm30 in an axial view. Thus, in the conventional vibration isolation unit,there is a problem that the number of parts, man-hour and material costincrease with provision of the stopper rubber, and the product costincreases as much.

SUMMARY OF THE INVENTION

The present invention has been developed in order to address the problemdescribed above, and its object is to provide a vibration isolation unitcapable of reducing the number of parts, man-hour and material cost andsuppressing the product cost.

According to a first aspect of the present invention, there is provideda vibration isolation unit including: a liquid-sealed vibrationisolation device including a cylindrical outer tube member, a bossmember positioned on the lower end side of the outer tube member, avibration isolation base body connecting the boss member and the outertube member to each other and formed of a rubber-like elastic body, adiaphragm attached on the upper end side of the outer tube member,forming a liquid-sealed chamber between the vibration isolation basebody and the diaphragm and formed of a rubber-like elastic body, apartition member partitioning the liquid-sealed chamber into a firstliquid chamber on the vibration isolation base body side and a secondliquid chamber on the diaphragm side, and an orifice allowing the firstliquid chamber and the second liquid chamber to communicate with eachother; an engine side bracket including a pressed-in part to which theouter tube member of the liquid-sealed vibration isolation device ispressed-in and which is connected to the engine side; a vehicle bodyside bracket including a bottom surface to which the boss member of theliquid-sealed vibration isolation device is fixed, a pair of side wallserected from the bottom surface and opposing to each other embracing theliquid-sealed vibration isolation device, and an upper surfaceconnecting the pair of side walls to each other and opposing the bottomsurface embracing the liquid-sealed vibration isolation device, andconnected to a vehicle body side; and a stopper rubber member interposedbetween the side wall of the vehicle body side bracket and thepressed-in part of the engine side bracket and formed of a rubber-likeelastic body. The stopper rubber member includes stopper rubber uppersurfaces of which one side continues to an outer edge of the diaphragmand which are disposed on the upper end side of the pressed-in part ofthe engine side bracket, and stopper rubber side walls hung down fromthe other side of the stopper rubber upper surfaces and disposed betweenthe side walls of the vehicle body side bracket and the pressed-in partof the engine side bracket.

According to the vibration isolation unit of the first aspect of thepresent invention, relative displacement in the axial direction of theouter tube member with respect to the boss member is damped andrestricted because the stopper rubber upper surfaces of the stopperrubber member abut on the upper surface of the vehicle body sidebracket, and relative displacement in the direction perpendicular to theaxis of the outer tube member with respect to the boss member is dampedand restricted because the stopper rubber side walls of the stopperrubber member abut on the side walls of the vehicle body side bracket.

In this case, one side of the stopper rubber upper surface of thestopper rubber member continues to an outer edge of the diaphragm, thatis, the stopper rubber member and the diaphragm are formed integrally.Thus, the number of parts can be reduced compared with a conventionalone in which the stopper rubber member is required to be vulcanizinglymolded as a single body separately from the diaphragm because thestopper rubber member and the diaphragm can be vulcanizingly moldedsimultaneously. Also, because the diaphragm is attached to the outertube member, the stopper rubber member is also fixed simultaneously.Accordingly, contrary to related art, it is not required to control toconfirm that the fixing rubber piece is properly held as in related art,and therefore the man-hour can be reduced as much. Further, overlappingof a part of the stopper rubber member with a part of the diaphragm inan axial view which occurs in the conventional one can be avoided, andrubber material can be used efficiently because the stopper rubber uppersurfaces continue to the outer edge of the diaphragm. Thus, according tothe vibration isolation unit of the first aspect of the presentinvention, the number of parts, man-hour and material cost can bereduced, and the product cost of the overall vibration isolation unitcan be suppressed.

In the vibration isolation unit according to the first aspect of thepresent invention, an annular attaching member to which the diaphragm isvulcanizingly adhered and which is formed of a resin material into anannular shape when viewed in the axial direction. The outer tube memberis formed of a resin material into a cylindrical shape, and thediaphragm is attached to the upper end side of the outer tube member bythat the annular attaching member is welded to the outer tube member byultrasonic welding. The vibration isolation unit with this structure maybe referred to as a second aspect of the present invention.

According to the vibration isolation unit of a second aspect of thepresent invention, workability can be improved because the outer tubemember and the annular attaching member are formed of a resin materialand the diaphragm can be attached to the outer tube member by weldingthe annular attaching member to the outer tube member by ultrasonicwelding.

That is, the upper surface of the annular attaching member is covered bya rubber-like elastic body because the stopper rubber upper surfaces ofthe stopper rubber member continue to the outer edge of the diaphragm.Accordingly, in a structure in which the annular attaching member ispressed-in to the outer tube member for example, a part on which apress-in implement is to be abutted cannot be secured in the uppersurface of the annular attaching member, it is required to directlypress the rubber-like elastic body covering the upper surface thereof,and therefore the workability is inferior. Also, when the rubber-likeelastic body is partly omitted and a part of the upper surface of theannular attaching member is exposed in order to make the press-inimplement abut thereupon, a damping action in exerting the stopperfunction deteriorates and an abnormal sound is generated.

In the vibration isolation unit according to the second aspect of thepresent invention, the annular attaching member includes an annular partto which the diaphragm is vulcanizingly adhered and a tubular partconnected to the lower surface side of the annular part, formed into acylindrical shape, and internally fitted to the inner peripheral side orexternally fitted to the outer peripheral side of the outer tube member,and the outer tube member and the tubular part of the annular attachingmember are welded to each other by subjecting the outer peripheral sideof the outer tube member to which the tubular part of the annularattaching member is internally fitted on the inner peripheral side orthe outer peripheral side of the tubular part of the annular attachingmember externally fitted to the outer peripheral side of the outer tubemember to ultrasonic welding. The vibration isolation unit with thisstructure may be referred to as a third aspect of the present invention.

According to the vibration isolation unit of the third aspect of thepresent invention, by subjecting the outer peripheral side of the outertube member to which the tubular part of the annular attaching member isinternally fitted to the inner peripheral side or the outer peripheralside of the tubular part of the annular attaching member externallyfitted to the outer peripheral side of the outer tube member toultrasonic welding, the outer tube member and the tubular part of theannular attaching member can be welded to each other because the annularattaching member includes a tubular part internally fitted to the innerperipheral side or externally fitted to the outer peripheral side of theouter tube member. That is, ultrasonic welding can be performed whileavoiding an adhering boundary surface where the diaphragm and an annularpart of the annular attaching member are vulcanizingly adhered with eachother. As a result, the adhering boundary surface between the diaphragmand the annular part of the annular attaching member can be suppressedfrom being peeled off by an ultrasonic wave.

In the vibration isolation unit according to the third aspect, the outertube member includes a large-diameter tube part positioned on the lowerend side and a small-diameter tube part formed to have a diametersmaller than that of the large-diameter tube part and positioned on theupper side, with the large-diameter tube part pressed-in to thepressed-in part of the engine side bracket, and the tubular part of theannular attaching member is internally fitted to the inner peripheralside of the small-diameter tube part of the outer tube member. Thevibration isolation unit with this structure may be referred to as afourth aspect of the present invention.

According to the vibration isolation unit of the fourth aspect of thepresent invention, the outer tube member includes the large-diametertube part positioned on the lower end side and the small-diameter tubepart formed to have a smaller diameter than that of the large-diametertube part and positioned on the upper end side, the large-diameter tubepart is pressed-in to the pressed-in part of the engine side bracket,the tubular part of the annular attaching member is internally fitted tothe inner peripheral side of the small-diameter tube part of the outertube member, and therefore a space can be formed between the outerperipheral surface of the small-diameter tube part of the outer tubemember and the inner peripheral surface of the pressed-in part of theengine side bracket. Thus, in performing ultrasonic welding from theouter peripheral side of the small-diameter tube part of the outer tubemember, a working space for a horn can be secured, and thereforeworkability of ultrasonic welding can be improved.

Also, with this configuration, the upper end surface of the pressed-inpart of the engine side bracket does not need to be positioned lowerthan the upper end surface of the small-diameter tube part of the outertube member (that is, to be retracted to a direction departing from theupper surface of the vehicle body side bracket), and the upper endsurface of the pressed-in part of the engine side bracket can bearranged at a position similar to that of the upper end surface of thesmall-diameter tube part of the outer tube member (or the upper endsurface of the annular attaching member). Thus, in exerting the stopperfunction, a pressure receiving area of the stopper rubber upper surfaceof the stopper rubber member can be secured, and durability thereof canbe improved. Also, durability of the outer tube member (or the annularattaching member) and the engine side bracket can be improved because areaction force from the upper surface of the vehicle body side bracketcan be shared by both of the upper end surface of the small-diametertube part of the outer tube member (or the upper end surface of theannular attaching member) and the upper end surface of the pressed-inpart of the engine side bracket.

In the vibration isolation unit according to the fourth aspect of thepresent invention, in the annular attaching member, an outer edgeportion of the annular part is formed so as to extend outward in theradial direction from the tubular part, and the lower surface of theouter edge portion of the annular part formed so as to extend outward inthe radial direction from the tubular part is made to abut on an upperend surface of the small-diameter tube part of the outer tube member.The vibration isolation unit with this structure may be referred to as afifth aspect of the present invention.

According to the vibration isolation unit of the fifth aspect of thepresent invention, the annular attaching member is formed so that theouter edge part of the annular part is extended outward in the radialdirection from the tubular part, the lower surface of the outer edgepart of the annular part formed so as to extend outward in the radialdirection from the tubular part is made to abut on the upper end surfaceof the small-diameter tube part of the outer tube member, thereforeworkability in performing ultrasonic welding can be improved, andbreakage of the welded part accompanying exertion of the stopperfunction can be prevented.

That is, in internal fitting (inserting) of the tubular part of theannular attaching member to the inner peripheral side of thesmall-diameter tube part of the outer tube member, the tubular part canbe positioned in the inserting direction because the outer edge part ofthe annular part formed so as to extend from the tubular part outward inthe radial direction is made to abut on the upper end surface of thesmall-diameter tube part of the outer tube member, and thereforeworkability can be improved as much.

Also, when relative displacement in the axial direction of the outertube member with respect to the boss member is restricted by the uppersurface of the vehicle body side bracket, the reaction force generatedin restricting can be received by the engagement section of the outeredge part of the annular part of the annular attaching member and theupper end surface of the small-diameter tube part of the outer tubemember because the outer edge part of the annular part formed so as toextend from the tubular part outward in the radial direction is made toabut on the upper end surface of the small-diameter tube part of theouter tube member thus. Accordingly, a force applied to the weld sectionof the tubular part of the annular attaching member and thesmall-diameter tube part of the outer tube member can be reduced asmuch.

In the vibration isolation unit according to the first aspect of theinvention, the liquid-sealed vibration isolation device includes adecompressing-cum-pouring hole allowing the liquid-sealed chamber tocommunicate with the outside and a sealer sealing thedecompressing-cum-pouring hole, and is manufactured by filling theliquid-sealed chamber with liquid by pouring the liquid through thedecompressing-cum-pouring hole after decompressing inside of theliquid-sealed chamber through the decompressing-cum-pouring hole, andsealing the decompressing-cum-pouring hole by the sealer, and thedecompressing-cum-pouring hole is disposed in the annular attachingmember. The vibration isolation unit with this structure may be referredto as a sixth aspect of the invention.

According to the vibration isolation unit of the sixth aspect of thepresent invention, assembling of the liquid-sealed vibration isolationdevice (filling the liquid-sealed chamber with liquid) can be performedafter the outer tube member is pressed-in to the pressed-in part of theengine side bracket because the liquid-sealed vibration isolation deviceincludes the decompressing-cum-pouring hole that allows theliquid-sealed chamber to communicate with the outside and a sealer thatseals the decompressing-cum-pouring hole, and, as a result, assemblingequipment can be made compact and the efficiency of the manufacturingprocess can be improved.

That is, in the vibration isolation unit of the sixth aspect of thepresent invention, in order to press-in the outer tube member of theliquid-sealed vibration isolation device to the pressed-in part of theengine side bracket after assembling the liquid-sealed vibrationisolation device in the liquid, it is required to fold the stopperrubber member so as not to be obstructive in pressing-in, and theman-hour increases because the diaphragm and the stopper rubber memberare formed integrally. On the other hand, when the outer tube member ispressed-in to the pressed-in part of the engine side bracket beforehandand the partition member, diaphragm and the like are thereafterassembled to them in the liquid, it is required to sink the engine sidebracket also into the liquid, and the storage tank storing the liquidbecomes large. To the contrary, according to the vibration isolationunit of the sixth aspect of the present invention, after the outer tubemember is pressed-in to the pressed-in part of the engine side bracket,the partition member, diaphragm and the like are assembled in theatmosphere and the liquid-sealed chamber can be filled with the liquidby vacuum suction, therefore the process for folding the stopper rubbermember is not required, and the efficiency of the manufacturing processcan be improved. Also, the storage tank is not required and theassembling equipment can be made compact because there is no work in theliquid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view of the vibration isolation unit of a firstembodiment of the present invention, and FIG. 1B is a front view of thevibration isolation unit when viewed from the direction of the arrow Ibof FIG. 1A.

FIG. 2 is a cross-sectional view of the vibration isolation unit takenfrom the line II-II of FIG. 1A.

FIG. 3A is a diagonal view of the diaphragm and the stopper rubbermember, and FIG. 3B is a diagonal view of the annular attaching member.

FIG. 4A is a bottom view of the diaphragm and the stopper rubber memberwhen viewed in the arrow IVa direction of FIG. 3A, and FIG. 4B is across-sectional view of the diaphragm and the stopper rubber membertaken from the line IVb-IVb of FIG. 4A.

FIG. 5 is a top view of the partition member.

FIG. 6A is a side view of the partition member when viewed in thedirection of the arrow VIa of FIG. 5, and FIG. 6B is a cross-sectionalview of the partition member taken from the line VIb-VIb of FIG. 5.

FIG. 7A is a cross-sectional view of a first molded body, and FIG. 7B isa cross-sectional view of the engine side bracket and the first moldedbody.

FIG. 8A is a cross-sectional view of a first unit, and FIG. 8B is apartially enlarged cross-sectional view of the first unit.

FIG. 9 is a cross-sectional view of the vibration isolation unit in thesecond embodiment.

FIG. 10A is a top view of the diaphragm, and FIG. 10B is across-sectional view of the diaphragm taken from the line Xb-Xb in FIG.10A.

FIG. 11A is a top view of the annular attaching member, and FIG. 11B isa cross-sectional view of the annular attaching member taken from theline XIb-XIb in FIG. 11A.

FIG. 12 is a partially enlarged cross-sectional view of the first unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred examples of the present invention will bedescribed referring to the attached drawings. First, the overallconstitution of a vibration isolation unit 1 will be described referringto FIG. 1A, FIG. 1B and FIG. 2.

FIG. 1A is a top view of the vibration isolation unit 1 of a firstembodiment of the present invention, and FIG. 1B is a front view of thevibration isolation unit 1 when viewed from the direction of the arrowIb of FIG. 1A. FIG. 2 is a cross-sectional view of the vibrationisolation unit 1 taken from the line II-II of FIG. 1A. Further, FIG. 2corresponds to a cross section including the axis O. Furthermore, inFIG. 2, a bolt is illustrated not by the cross-sectional view.

As shown in FIG. 1A, FIG. 1B and FIG. 2, the vibration isolation unit 1is a device for suppressing vibration of an engine (not shown) of anautomobile from being transmitted to a vehicle body (not shown) whilesupporting and fixing the engine, and includes a vibration isolationdevice 10 in which a boss member 11 and an outer tube member 12 areconnected to each other by a vibration isolation base body 13, an engineside bracket 20 holding the outer tube member 12 of the vibrationisolation device 10 and attached to the engine side, and a vehicle bodyside bracket 30 to which the boss member 11 of the vibration isolationdevice 10 is fixed and which is attached to the vehicle body side.

The vibration isolation device 10 is arranged at a vertical attitude inwhich the axis O direction agrees with the vertical direction, isarranged in an inverted state in which the boss member 11 side comes tothe downward side, and is surrounded by the vehicle body side bracket 30that is formed into a frame shape in a front view. The engine sidebracket 20 is extended horizontally from a side of the vibrationisolation device 10 outward in the radial direction (directionperpendicular to the axis O, upward in FIG. 1A).

In a state that the vibration isolation unit 1 supports and fixes theengine of an automobile to the vehicle body (so-called 1 W state), thevibration isolation base body 13 is compressingly deformed (that is, theouter tube member 12 is displaced so as to approach the boss member 11)by the weight of the engine, and a predetermined gap is formedcorrespondingly between the upper end side (a diaphragm 14 side) of thevibration isolation device 10 and an upper surface 33 of the vehiclebody side bracket 30. In this case, the diaphragm 14 is inflated towardthe side opposite to a partition member 15. Also, in FIG. 1A, FIG. 1Band FIG. 2, a state before the engine is supported and fixed (no-loadstate) is shown.

The vibration isolation device 10 mainly includes the boss member 11attached to the vehicle body side through the vehicle body side bracket30, the outer tube member 12 of a cylindrical shape attached to theengine side through the engine side bracket 20, and the vibrationisolation base body 13 connecting both the members 11, 12 to each otherand formed of a rubber-like elastic body. The boss member 11 is formedof an aluminum alloy to have a cross-sectional shape of a generallytruncated cone that narrows as it goes upward, and the lower surfaceside (lower side in FIG. 2) is fastened and fixed to a bottom surface 31of the vehicle body side bracket 30 by a bolt.

The outer tube member 12 is formed of a resin material into acylindrical shape in which upper and lower ends (upper side and lowerside in FIG. 2) open, and is disposed above (upper side in FIG. 2) theboss member 11 so as to be coaxial with each other. Also, the outer tubemember 12 is constituted so as to have a step, a large-diameter tubepart 12 a with a large diameter is formed on the lower side (lower sidein FIG. 2) of the step and a small-diameter tube part 12 b with a smalldiameter is formed on the upper side (upper side in FIG. 2) of the step.Further, on the lower end side of the large-diameter tube part 12 a, aflange-like extended part 12 c extending outward in the radial directionis formed. The outer tube member 12 is held in a state that thelarge-diameter tube part 12 a is pressed-in to the pressed-in part 21 ofthe engine side bracket 20 in the axis O direction and the extended part12 c abuts on the lower end surface of the pressed-in part 21 of theengine side bracket 20.

The vibration isolation base body 13 is formed of a rubber-like elasticbody to have a cross-sectional shape of a generally truncated cone thatnarrows as it goes downward which is symmetric around the axis O, and isvulcanizingly adhered between the outer surface of the boss member 11and the inner wall surface of the outer tube member 12 (the portions ofthe large-diameter tube part 12 a and the step). A membrane-like rubbermembrane continues to an end on the outer tube member 12 side of thevibration isolation base body 13, and the inner wall surface of thesmall-diameter tube part 12 b of the outer tube member 12 is covered bythe rubber membrane.

On the upper end side (upper side in FIG. 2) of the outer tube member12, the diaphragm 14 is furnished in a close contact (watertight) state.Thus, a liquid-sealed chamber 16 into which liquid is sealed is formedbetween the lower surface side of the diaphragm 14 and the upper surfaceside of the vibration isolation base body 13. Into the liquid-sealedchamber 16, antifreezing liquid (not shown) such as ethylene glycol andthe like is sealed. The partition member 15 is a member partitioning theliquid-sealed chamber 16 into a first liquid chamber 16A on thevibration isolation base body 13 side and a second liquid chamber 16B onthe diaphragm side, and on the outer peripheral side thereof, an orifice17 is formed which is a flow passage allowing the first liquid chamber16A and the second liquid chamber 16B to communicate with each other.

Also, the liquid-sealed chamber 16 is filled with the liquid byassembling the vibration isolation unit 1 (vibration isolation device10), thereafter decompressing inside the liquid-sealed chamber 16 byvacuum suction through a decompressing-cum-pouring hole 44 c (refer toFIG. 4A and FIG. 4B) to obtain a negative pressure, then pouring theliquid through the decompressing-cum-pouring hole 44 c into theliquid-sealed chamber 16 utilizing the negative pressure.

The diaphragm 14 is formed into a membrane shape having a partial sphereshape inflated to the partition member 15 side and symmetric around theaxis O, and to the outer peripheral edge thereof, a stopper rubbermember 42 continues which covers the upper surface side of the vibrationisolation device 10 and the outer peripheral side of a pressed-in part21 of the engine side bracket 20. That is, the diaphragm 14 and thestopper rubber member 42 are formed integrally of a rubber-like elasticbody.

Also, the diaphragm 14 and the stopper rubber member 42 arevulcanizingly adhered to an annular attaching member 44 formed of aresin material into an annular shape when viewed in the axis Odirection. The diaphragm 14 and the stopper rubber member 42 areattached to the outer tube member 12 because the annular attachingmember 44 is internally fitted on the upper end side of the outer tubemember 12 and is connected by ultrasonic welding.

The partition member 15 includes an orifice forming part 51 positionedon the outer peripheral side, a displacement restricting part 52integrally formed on the inner peripheral surface side of the orificeforming part 51, a displacement restricting part 53 disposed on thelower end side of the orifice forming part 51 and opposing thedisplacement restricting part 52 at a predetermined interval, and anelastic partition membrane 54 stored between opposing surfaces of thepair of displacement restricting parts 52, 53 in a freely movablemanner.

The engine side bracket 20 includes the pressed-in part 21 of a flatplate shape and an extension part 22 of a block shape extended in anoblique direction from a corner on one side (right upper side in FIG.1A) of the pressed-in part 21, and they are integrally formed of analuminum alloy. A press-in hole of a circular shape in a top view isbored in the pressed-in part 21, and the vibration isolation device 10(outer tube member 12) is held by the engine side bracket 20 because theouter tube member 12 is pressed-in to the press-in hole in the axis Odirection.

Also, the inside diameter of the press-in hole bored in the pressed-inpart 21 is made generally constant along the axis O direction.Accordingly, in a step of welding the outer tube member 12 and theannular attaching member 44 with each other by ultrasonic welding, aspace to which a horn that performs ultrasonic welding is inserted canbe formed on the outer peripheral side of the weld section (refer toFIG. 8A) while securing strength of the pressed-in part 21 and reducingthe manufacturing cost thereof.

The vehicle body side bracket 30 includes the bottom surface 31 to whichthe boss member 11 of the vibration isolation device 10 is fastened andfixed, a pair of side walls 32 erected from the bottom surface 31 andopposing to each other embracing the vibration isolation device 10, andan upper surface 33 connecting the upper ends of the pair of side walls32 that have been erected to each other and opposing the bottom surface31 embracing the vibration isolation device 10, and they are integrallyformed of an aluminum alloy. In inputting vibration of large amplitude,relative displacement of a predetermined magnitude or more of the outertube member 12 with respect to the boss member 11 is restricted becausethe vehicle body side bracket 30 formed into a frame shape in a frontview surrounds the periphery of the vibration isolation device 10.

Also, in the engine side bracket 20, attaching holes h1 are bored atplural positions (three positions in the present embodiment) of thepressed-in part 21 and the extension part 22, and the engine sidebracket 20 is fastened and fixed to the engine side by bolts insertedinto the respective attaching holes h1. Further, in the vehicle bodyside bracket 30, attaching holes h2 are bored at plural positions (threepositions in the present embodiment) of the bottom surface 31, and thevehicle body side bracket 30 is fastened and fixed to the vehicle bodyside by bolts inserted into the respective attaching holes h2.

Next, referring to FIG. 3A, FIG. 3B, FIG. 4A and FIG. 4B, detailedconstitution of the diaphragm 14 and the stopper rubber member 42 willbe described. As described above, according to the present embodiment,the diaphragm 14 and the stopper rubber member 42 are integrally formed.

FIG. 3A is a diagonal view of the diaphragm 14 and the stopper rubbermember 42, and FIG. 3B is a diagonal view of the annular attachingmember 44. Also, FIG. 4A is a bottom view of the diaphragm 14 and thestopper rubber member 42 when viewed in the arrow IVa direction of FIG.3A, and FIG. 4B is a cross-sectional view of the diaphragm 14 and thestopper rubber member 42 taken from the line IVb-IVb of FIG. 4A. In FIG.4A and FIG. 4B, illustration of a part of the stopper rubber member 42is omitted.

As shown in FIG. 3A, FIG. 3B, FIG. 4A and FIG. 4B, the stopper rubbermember 42 includes stopper rubber upper surfaces 42 a one side of whichcontinues to the outer edge of the diaphragm 14 and which are extendedoutward in the radial direction, and stopper rubber side walls 42 b hungdown from the other side of the stopper rubber upper surfaces 42 a.Also, with respect to the stopper rubber upper surfaces 42 a and thestopper rubber side walls 42 b, one pair of each is formed on both sidesof the diaphragm 14 embracing the axis O.

The stopper rubber upper surfaces 42 a are portions of a flat plateshape disposed on the upper end side of the outer tube member 12 of thevibration isolation device 10 and on the upper end side of thepressed-in part 21 of the engine side bracket 20, and are made to abuton the bottom surface 31 of the vehicle body side bracket 30 when theouter tube member 12 is displaced toward the axis O relative to the bossmember 11. On the upper surface of the stopper rubber upper surfaces 42a, plural projections are projected toward the bottom surface 31 of thevehicle body side bracket 20.

The stopper rubber side walls 42 b are portions of a flat plate shapedisposed between the pressed-in part 21 of the engine side bracket 20and the side walls 32 of the vehicle body side bracket 30, and is madeto abut on the side walls 32 of the vehicle body side bracket 30 whenthe outer tube member 12 is displaced toward the axis O relative to theboss member 11. On the side surface of the stopper rubber side walls 42b, plural projections are projected toward the side walls 32 of thevehicle body side bracket 30.

As described above, according to the present embodiment, one side of thestopper rubber upper surface 42 a of the stopper rubber member 42continues to the outer edge of the diaphragm 14, and the stopper rubbermember 42 and the diaphragm 14 are formed integrally. Thus, because thestopper rubber member 42 and the diaphragm 14 can be vulcanizinglymolded simultaneously, the number of parts can be reduced compared to aconventional one in which the stopper rubber member needs to bevulcanizingly molded as a single body separately from the diaphragm.

Also, the stopper rubber member 42 can be fixed (mounted) simultaneouslybecause the diaphragm 14 is attached to the outer tube member 12 (referto FIG. 8A). That is, because, contrary to related art, it is notrequired to control to confirm whether the fixing rubber piece isproperly held, the man-hour can be reduced as much.

Further, overlapping of a part of the stopper rubber member with a partof the diaphragm in an axial view which occurs in the conventional onecan be avoided because the stopper rubber upper surface 42 a continuesto the outer edge of the diaphragm 14. That is, the rubber material ofthe overlapping portion is not wasted, and the rubber material can beused efficiently.

The annular attaching member 44 includes an annular part 44 a formedinto a flat plate shape of an annular shape in a top view (when viewedin the axis O direction) and a tubular part 44 b hung down from thelower surface of the annular part 44 a and formed into a tubular shape.The annular part 44 a and the tubular part 44 b are formed into a shapesymmetric around the axis O, the inside diameter of the annular part 44a is made smaller than the inside diameter of the tubular part 44 b, theoutside diameter of the annular part 44 a is made larger than theoutside diameter of the tubular part 44 b, and thereby the shape of across section including the axis O is formed into a T-shape. The annularpart 44 a is formed to have an outside diameter generally equal to anoutside diameter of the small-diameter tube part 12 b of the outer tubemember 12.

The diaphragm 14 and the stopper rubber member 42 are vulcanizinglyadhered to the upper surface, inner peripheral surface and lower surfaceof the annular part 44 a and a part of the inner peripheral surface ofthe tubular part 44 b. Also, the tubular part 44 b is internally fittedto the small-diameter tube part 12 b of the outer tube member 12 fromthe upper end side, the tubular part 44 b and the small-diameter tubepart 12 b are welded to each other by ultrasonic welding, and therebythe diaphragm 14 and the stopper rubber member 42 are attached to theouter tube member 12 (refer to FIG. 2).

As described above, the annular attaching member 44 is formed of a resinmaterial along with the outer tube member 12 and the outer tube member12 and the annular attaching member 44 are connected (joined) to eachother by ultrasonic welding, thereby workability in attaching thediaphragm 14 to the outer tube member 12 can be improved, and generationof an abnormal sound can be suppressed.

That is, according to the present embodiment, the upper surface of theannular attaching member 44 is covered by the rubber-like elastic body(diaphragm 14 or the stopper rubber upper surfaces 42 a) because thestopper rubber upper surfaces 42 a of the stopper rubber member 42continue to the outer edge of the diaphragm 14.

Accordingly, for example, in a structure in which the annular attachingmember 44 is pressed-in and fixed to the small-diameter tube part 12 bof the outer tube member 12 (that is, the outside diameter of thetubular part 44 b of the annular attaching member 44 is made slightlylarger than the inside diameter of the small-diameter tube part 12 b ofthe outer tube member 12, thereby an interference is generated forpressing-in and fixing), a portion (area) on which a press-in tool usedwhen the annular attaching member 44 is pressed-in to the outer tubemember 12 abuts cannot be secured on the upper surface of the annularattaching member 44, and it is required to directly press therubber-like elastic body covering the upper surface thereof.Accordingly, workability is inferior.

On the other hand, when the rubber-like elastic body is partly omittedand a part of the upper surface of the annular attaching member 44 isexposed in order to allow the press-in implement to abut thereupon, thevolume of the rubber-like elastic body for exerting the stopper functionis reduced as much. Accordingly, the damping action in exerting thestopper function is reduced and an abnormal sound is generated.

In this case, as described below, by subjecting the outer peripheralside of the small-diameter tube part 12 b of the outer tube member 12with the tubular part 44 b of the annular attaching member 44 beinginternally fitted to the inner peripheral side thereof to ultrasonicwelding, the small-diameter tube part 12 b of the outer tube member 12and the tubular part 44 b of the annular attaching member 44 can bewelded to each other because the annular attaching member 44 includesthe tubular part 44 b of a cylindrical shape hung down from the lowersurface of the annular part 44 a, (refer to FIG. 8A). That is,ultrasonic welding can be performed while avoiding the adhering boundarysurface where the diaphragm 14 and the stopper rubber member 42 arevulcanizingly adhered to the annular attaching member 44. As a result,the adhering boundary surface between the diaphragm 14 and the stopperrubber member 42 and the annular attaching member 44 can be suppressedfrom being peeled off by an ultrasonic wave.

As shown in FIG. 4A, plural projections (five in the present embodiment)of a semicircle shape when viewed in the axis O direction are projectedinward in the radial direction in the annular attaching member 44, andthe decompressing-cum-pouring hole 44 c is formed in one of theprojections. The projection where the decompressing-cum-pouring hole 44c is formed out of the plural projections is formed by that the annularpart 44 a and the tubular part 44 b partly project, and otherprojections are formed by that only the tubular part 44 b partlyprojects.

The decompressing-cum-pouring hole 44 c is a through hole used indecompressing the inside of the liquid-sealed chamber 16 by vacuumsuction, and is formed as a through hole penetrating the annularattaching member 44 (the annular part 44 a and the tubular part 44 b).The inside of the liquid-sealed chamber 16 and the outside are made tocommunicate with each other by the decompressing-cum-pouring hole 44 c(refer to FIG. 8B).

Thus, the annular attaching member 44 is formed into an annular shapewhen viewed in the axial direction, the diaphragm 14 is vulcanizinglyadhered to the inner peripheral edge of the annular attaching member 44,and the decompressing-cum-pouring hole 44 c is disposed on the outerside in the radial direction (the left side in FIG. 4B) of the innerperipheral edge of the annular attaching member 44. Accordingly, theouter edge of the diaphragm 14 can be surely vulcanizingly adhered tothe inner peripheral edge of the annular attaching member 44 over theentire periphery, and formation of the decompressing-cum-pouring hole 44c in a movable part (a membrane part) of the diaphragm 14 can beavoided. As a result, durability of the diaphragm 14 can be improved.

Also, the decompressing-cum-pouring hole 44 c is sealed (is made anon-communicating state, refer to FIG. 8B) by a sealer (for example, aknown unit such as a hard ball, rivet and the like) not shown after theinside of the liquid-sealed chamber 16 has been decompressed and fillingthe liquid-sealed chamber 16 with the liquid has been completed.

Further, an area of the diaphragm 14 and the stopper rubber member 42(the stopper rubber upper surface 42 a) corresponding to thedecompressing-cum-pouring hole 44 c is recessedly cut off partly in acircular shape in a top view. That is, around an opening on the outerside (the upper side in FIG. 4B) of the decompressing-cum-pouring hole44 c, the diaphragm 14 and the stopper rubber member 42 are notdisposed, and the upper surface of a flat plane shape of the annularpart 44 a of the annular attaching member 44 is exposed.

Thus, because the upper surface of the annular attaching member 44 wherethe decompressing-cum-pouring hole 44 c opens is formed into a flatplane, when a pipe is furnished to the decompressing-cum-pouring hole 44c in a step of decompressing the inside of the liquid-sealed chamber 16and a step of filling the liquid, the periphery thereof can be surelysealed by utilizing the flat plane of the upper surface of the annularattaching member 44 as a seat surface.

That is, when the decompressing-cum-pouring hole 44 c is arranged on theside surface of the outer tube member 12 as done in a conventional one,because the outer surface of the outer tube member 12 is curved in acylindrical shape, it is difficult to make a seal lip arranged on thepipe side adhere tightly to the outer surface of the outer tube member12 without a gap due to the dimensional tolerance, the skill of a workerand the like. On the other hand, according to the present embodiment,the seal lip arranged on the pipe side can be adhered tightly without agap because the surface to be sealed is a flat plane.

Next, the detailed constitution of the partition member 15 will bedescribed referring to FIG. 5, FIG. 6A and FIG. 6B. FIG. 5 is a top viewof the partition member 15. FIG. 6A is a side view of the partitionmember 15 when viewed in the direction of the arrow VIa of FIG. 5, andFIG. 6B is a cross-sectional view of the partition member 15 taken fromthe line VIb-VIb of FIG. 5.

In the orifice forming part 51 of the partition member 15, extendedwalls 51 a, 51 b of a generally flange shape are formed so as to extendoutward in the radial direction. The orifice 17 is formed which is aflow passage allowing a first liquid chamber 16A and a second liquidchamber 16B to communicate with each other because the extended walls 51a, 51 b tightly adhere to a rubber membrane covering the inner wallsurface of the outer tube member 12 (refer to FIG. 2). Further, as shownin FIG. 6A, the orifice forming part 51 includes a vertical wall 51 cconnecting the upper and lower extended walls 51 a, 51 b, and theorifice 17 is divided in the peripheral direction by the vertical wall51 c.

The displacement restricting parts 52, 53 are portions of a plate shapereceiving the elastic partition membrane 54 and restricting thedisplacement thereof, and are formed into a lattice shape where pluralopenings are formed by plural (four in the present embodiment) ribs 52a, 53 a extended radially and linearly from the axis O. That is, thelattice shapes of the displacement restricting parts 52, 53 formed bythe ribs 52 a, 53 a are made same to each other.

The displacement restricting part 52 is formed integrally with the innerperipheral surface of the orifice forming part 51, and is disposed onthe side opposing the diaphragm 14. The displacement restricting part 53is formed into a disk shape having the outside diameter equal to that ofthe extended walls 51 a, 51 b of the orifice forming part 51, and isdisposed on the side opposing the vibration isolation base body 13. Theelastic partition membrane 54 is formed of a rubber-like elastic bodyinto a disk shape, and has a maximum membrane thickness in the centerwhich is made slightly smaller than the gap between the opposingsurfaces of the displacement restricting parts 52, 53.

In the extended wall 51 b of the orifice forming part 51 and thedisplacement restricting part 53, cutouts 51 d, 53 d are openinglyformed respectively at a same position in the peripheral direction, andone end of the orifice 17 is made to communicate with the first liquidchamber 16A (refer to FIG. 2) through an opening by both the cutouts 51d, 53 d. On the other hand, in the extended wall 51 a of the orificeforming part 51, a cutout 51 e is openingly formed, and the other end ofthe orifice 17 is made to communicate with the second liquid chamber 16B(refer to FIG. 2) through an opening by the cutout 51 e. The cutout 51 eis extended to a same position of the displacement restricting part 52.

Here, the partition member 15 is positioned in the peripheral direction(refer to FIG. 8B) so that the cutout 51 e is positioned right below thedecompressing-cum-pouring hole 44 c of the annular attaching member 44(to oppose the decompressing-cum-pouring hole 44 c) in a state that thevibration isolation device 10 is assembled (refer to FIG. 8A and FIG.8B).

Also, according to the present embodiment, as shown imaginarily bytwo-dot chain lines in FIG. 6A and FIG. 6B, in a state that thevibration isolation device 10 is assembled, an imaginary line P which isthe extension of the axis of the decompressing-cum-pouring hole 44 c ofthe annular attaching member 44 is positioned generally in the center ofthe length in the peripheral direction of the cutout 51 e (the dimensionin the right-left direction in FIG. 6A) and is positioned so as to shiftslightly to the axis O side from generally the center of the length inthe radial direction (the dimension in the right-left direction in FIG.6B) of the cutout 51 e.

Next, a method for manufacturing the vibration isolation unit 1 will bedescribed referring to FIG. 7A, FIG. 7B, FIG. 8A and FIG. 8B. FIG. 7A isa cross-sectional view of a first molded body, and FIG. 7B is across-sectional view of the engine side bracket 20 and the first moldedbody. FIG. 8A is a cross-sectional view of a first unit, and FIG. 8B isa partially enlarged cross-sectional view of the first unit.

In manufacturing the vibration isolation unit 1, first, the first moldedbody obtained by connecting the boss member 11 and the outer tube member12 by the vibration isolation base body 13, a second molded bodyobtained by integrally forming the diaphragm 14 and the stopper rubbermember 42 and connecting the annular attaching member 44 (refer to FIG.3A, FIG. 4A and FIG. 4B), and the elastic partition membrane 54 (referto FIG. 6B) are vulcanizing molded respectively. Also, the partitionmember 15 is assembled (that is, the elastic partition membrane 54 isstored between the opposing displacement restricting parts 52, 53, andthe displacement restricting part 53 is joined to the orifice formingpart 51; refer to FIG. 5, FIG. 6A and FIG. 6B).

After the first molded body and the second molded body have beenvulcanizingly molded and the partition member 15 has been assembled, asshown in FIG. 7A, the partition member 15 is fitted in to the inside ofthe outer tube member 12 of the first molded body. After the partitionmember 15 has been fitted in to the first molded body, the first moldedbody (the large-diameter tube part 12 a of the outer tube member 12) ispressed-in to the pressed-in part 21 of the engine side bracket 20.

Thus, as shown in FIG. 7B, the first molded body is held by the engineside bracket 20. In this case, the relative position in the peripheraldirection of the partition member 15 with respect to the engine sidebracket 20 is set to a predetermined position (that is, a position wherethe cutout 51 e of the orifice forming part 51 overlaps thedecompressing-cum-pouring hole 44 c when viewed in the axis O direction,refer to FIG. 9).

According to the present embodiment, the decompressing-cum-pouring hole44 c is formed in the annular attaching member 44 attached on the upperend side of the outer tube member 12 (refer to FIG. 8B). Accordingly, itis possible to prevent the disposal position of the partition member 15from being limited by the decompressing-cum-pouring hole 44 c. That is,when the decompressing-cum-pouring hole 44 c is formed on the sidesurface of the outer tube member 12 as done in a conventional one, it isnot possible to dispose the partition member 15 lower than the formationposition of the decompressing-cum-pouring hole 44 c (on the boss member11 side), and therefore the vibration isolation device 10 is enlargedtoward the axis O direction. On the other hand, according to the presentembodiment, the disposal position of the partition member 15 is notlimited, and the partition member 15 can be disposed at a position closeto the boss member 11 because the decompressing-cum-pouring hole 44 c isformed in the annular attaching member 44.

Further, when the decompressing-cum-pouring hole 44 c is formed on theside surface of the outer tube member 12 as done in a conventional one,decompressing and liquid filling of the inside of the liquid-sealedchamber 16 cannot be performed after the outer tube member 12 ispressed-in to the engine side bracket 20. On the other hand, even afterthe outer tube member 12 is pressed-in to the engine side bracket 20,decompression and liquid filling of the inside of the liquid-sealedchamber 16 can be performed because the decompressing-cum-pouring hole44 c is formed in the annular attaching member 44 (refer to FIG. 7B andFIG. 8A).

After the engine side bracket 20 is made to hold the first molded body,the second molded body is attached on the upper end side of the firstmolded body (that is, the tubular part 44 b of the annular attachingmember 44 in the second molded body is internally fitted to thesmall-diameter tube part 12 b of the outer tube member 12 in the firstmolded body), and the small-diameter tube part 12 b and the tubular part44 b are welded to each other by ultrasonic welding. Thus, as shown inFIG. 8A, the liquid-sealed chamber 16 (refer to FIG. 2) is formedbetween the vibration isolation base body 13 and the diaphragm 14.

In a step of performing ultrasonic welding, in inserting the tubularpart 44 b of the annular attaching member 44 to the inner peripheralside of the small-diameter tube part 12 b of the outer tube member 12,the outer edge portion of the annular part 44 a formed so as to extendoutward in the radial direction from the tubular part 44 b can be madeto abut on the upper end surface of the small-diameter tube part 12 b ofthe outer tube member 12 because the annular attaching member 44 isformed to have a T-shape cross section (refer to FIG. 4B). Thus, asshown in FIG. 8A, the tubular part 44 b can be positioned in theinserting direction (the axis O direction), and workability can beimproved as much.

In a state that the annular attaching member 44 is inserted to the outertube member 12, a space is formed between the outer peripheral surfaceof the small-diameter tube part 12 b of the outer tube member 12 and theinner peripheral surface of the pressed-in part 21 (press-in hole) ofthe engine side bracket 20 as shown in FIG. 8A. Accordingly, utilizingthis space, the horn can be moved, and therefore the workability can beimproved. In the step of performing ultrasonic welding, by folding backthe stopper rubber member 42 upward, the space can be exposedcontinuously in the peripheral direction.

Also, when a space can be formed thus between the outer peripheralsurface of the small-diameter tube part 12 b of the outer tube member 12and the inner peripheral surface of the pressed-in part 21 (press-inhole) of the engine side bracket 20, it is not necessary to position theupper end surface of the pressed-in part 21 of the engine side bracket20 lower than the upper end surface of the small-diameter tube part 12 bof the outer tube member 12, and the upper end surface of the pressed-inpart 21 of the engine side bracket 20 can be arranged in a positionsimilar to the upper surface of the annular part 44 a of the annularattaching member 44 (that is, a position close to the upper surface 33of the vehicle body side bracket 30) as shown in FIG. 8A.

Thus, when the outer tube member 12 is relatively displaced in the axisO direction with respect to the boss member 11 and the stopper rubberupper surfaces 42 a of the stopper rubber member 42 are made to abut onthe upper surface 33 of the vehicle body side bracket 30, the pressurereceiving area of the stopper rubber upper surfaces 42 a of the stopperrubber member 42 can be secured by utilizing both surfaces of the upperend surface of the pressed-in part 21 of the engine side bracket 20 andthe upper surface of the annular part 44 a of the annular attachingmember 44. As a result, durability of the stopper rubber member 42 canbe improved.

In a similar manner, when the stopper function is exerted, the reactionforce from the upper surface 33 of the vehicle body side bracket 30 canbe shared equally by both the upper end surface of the pressed-in part21 of the engine side bracket 20 and the upper surface of the annularpart 44 a of the annular attaching member 44. Accordingly, a reactionforce from the upper surface 33 is dispersed to the outer tube member12, the annular attaching member 44 and the engine side bracket 20, anddurability thereof can be improved.

Here, as described above, the annular attaching member 44 is welded tothe small-diameter tube part 12 b of the outer tube member 12 in a statethat the outer edge portion of the annular part 44 a formed so as toextend outward in the radial direction from the tubular part 44 b ismade to abut on the upper end surface of the small-diameter tube part 12b of the outer tube member 12 (that is, in a state that the outer edgeportion of the annular part 44 a engages with the upper end surface ofthe small-diameter tube part 12 b). Accordingly, when the relativedisplacement in the axial direction of the outer tube member 12 withrespect to the boss member 11 is restricted by the upper surface 33 ofthe vehicle body side bracket 30, the reaction force in restricting canbe received by an engaging portion of the outer edge portion of theannular part 44 a of the annular attaching member 44 and the upper endsurface of the small-diameter tube part 12 b of the outer tube member12. Accordingly, a force applied to the weld section between the outerperipheral surface of the tubular part 44 b of the annular attachingmember 44 and the inner peripheral surface of the small-diameter tubepart 12 b of the outer tube member 12 can be reduced as much. As aresult, damage of the weld section can be suppressed.

After the liquid-sealed chamber 16 has been formed, the inside of theliquid-sealed chamber 16 is decompressed until reaching a predeterminednegative pressure state by vacuum suction through thedecompressing-cum-pouring hole 44 c, thereafter the liquid is poured inthrough the decompressing-cum-pouring hole 44 c utilizing the negativepressure, and thereby the liquid-sealed chamber 16 is filled with theliquid.

In this case, in the step of vacuum suction of the inside of theliquid-sealed chamber 16, the air inside the first liquid chamber 16Acan be efficiently sucked through the orifice 17 along with sucking ofthe air inside the second liquid chamber 16B because thedecompressing-cum-pouring hole 44 c is arranged at a positionoverlapping with (a position opposing) the cutout 51 e of the partitionmember 15 when viewed in the axis O direction (refer to FIG. 6A and FIG.6B). Also, in the step of filling the liquid to the inside of theliquid-sealed chamber 16, the liquid can be efficiently delivered intothe first liquid chamber 16A through the orifice 17 along with fillingof the liquid into the second liquid chamber 16B.

After the liquid-sealed chamber 16 has been filled with the liquid, thedecompressing-cum-pouring hole 44 c is sealed by a hard ball B (sealer)made of an iron and steel material, a resin material and the like asshown in FIG. 8B. Thus, a first unit shown in FIG. 8B (that is, thevibration isolation device 10 held by the engine side bracket 20) isformed.

After the first unit has been formed, while the vibration isolation basebody 13 of the vibration isolation device 10 is compressed in the axis Odirection, the vibration isolation device 10 is arranged between theopposing surfaces of the bottom surface 31 and the upper surface 33 ofthe vehicle body side bracket 30, and the boss member 11 of thevibration isolation device 10 and the bottom surface 31 of the vehiclebody side bracket 30 are fastened and fixed to each other by the bolt.Thus, manufacturing of the vibration isolation unit 1 is completed(refer to FIG. 1A, FIG. 1B and FIG. 2).

Next, a vibration isolation unit 201 in a second embodiment will bedescribed referring to FIG. 9 to FIG. 12. Although the case where thediaphragm 14 and the stopper rubber member 42 are integrally formed isdescribed in the first embodiment, a stopper rubber member 242 in thesecond embodiment is formed as a body separate from a diaphragm 214.Also, a same reference sign is given to a part same to that of the firstembodiment, and description thereof is omitted.

FIG. 9 is a cross-sectional view of the vibration isolation unit 201 inthe second embodiment. In a vibration isolation device 210 in the secondembodiment, the stopper rubber member 242 is formed as a component of abody separate from the diaphragm 214. That is, in the stopper rubbermember 242, although stopper side walls 242 b are formed similarly tothe case of the first embodiment, a stopper upper surface 242 a isformed as a portion of one flat plate shape to which a pair of thestopper side walls 242 b is connected. The stopper upper surface 242 ais placed on the upper surface side (upper side in FIG. 9) of thevibration isolation device 210 and the engine side bracket 20 (thepressed-in part 21).

Also, an outer tube member 212 is formed of an iron and steel materialand holds an annular attaching member 244 by subjecting the upper end todiameter reducing work (caulking work). Further, with respect to theouter tube member 212, because the constitutions of respective portionsbefore performing caulking work are similar to the constitutions of therespective portions (the large-diameter tube part 12 a, thesmall-diameter tube part 12 b and the extended part 12 c) in the firstembodiment with the exception that the raw material is different, thesame reference signs as them are given, and description thereof isomitted.

Next, the diaphragm 214 and the annular attaching member 244 will bedescribed referring to FIG. 10A, FIG. 10B, FIG. 11A and FIG. 11B. FIG.10A is a top view of the diaphragm 214, and FIG. 10B is across-sectional view of the diaphragm 214 taken from the line Xb-Xb inFIG. 10A. Also, FIG. 11A is a top view of the annular attaching member244, and FIG. 11B is a cross-sectional view of the annular attachingmember 244 taken from the line XIb-XIb in FIG. 11A.

As shown in FIG. 10A, FIG. 10B, FIG. 11A and FIG. 11B, the diaphragm 214is formed into a membrane shape having a partial sphere shape inflatedto the partition member 15 side and symmetric around the axis O, and isvulcanizingly adhered to the upper surface and the inner peripheralsurface of the annular attaching member 244. The annular attachingmember 244 is formed of an iron and steel material into a flat plateshape of an annular shape in a top view (when viewed in the axis Odirection), and a projection of a semicircle shape in a top view isarranged so as to project inward in the radial direction. Adecompressing-cum-pouring hole 244 c is formed in the projection.

The outside diameter of the diaphragm 214 is made smaller than theoutside diameter of the annular attaching member 244. Thereby, at theouter edge of the upper surface of the annular attaching member 244, anarea exposed in an annular shape in a top view (that is, an area forallowing the upper end of the outer tube member 212 that has beendeformed so as to reduce the diameter (deformed so as to be folded back)to engage thereto in fixing by caulking) is formed.

Also, the outside diameter of the annular attaching member 244 is madegenerally equal to the outside diameter of the partition member 15. Thatis, in a state that the annular attaching member 244 is fitted in to theinside of the outer tube member 212, the outer peripheral surface of theannular attaching member 244 is tightly attached to a rubber membranethat covers the inner wall surface of the small-diameter tube part 12 bof the outer tube member 212.

The formation position of the decompressing-cum-pouring hole 244 c isarranged on the inner side in the radial direction (on the axis O side)of the outer edge of the diaphragm 214. Accordingly, even after theupper end of the outer tube member 212 has been fixed by caulking, it ispossible to furnish a pipe to the decompressing-cum-pouring hole 244 cand to decompress the inside of the liquid-sealed chamber 16 and fill itwith the liquid.

Also, in the diaphragm 214, an area corresponding to thedecompressing-cum-pouring hole 244 c is partially recessedly cut off ina semicircular shape in a top view. That is, around an opening of thedecompressing-cum-pouring hole 244 c, the diaphragm 214 is not disposed,and the upper surface of a flat plane shape of the annular attachingmember 244 is exposed. Accordingly, similarly to the case of the firstembodiment, the upper surface of the annular attaching member 244 can beutilized as a seat surface, and sealing performance in furnishing thepipe can be improved.

Next, a method for manufacturing the vibration isolation unit 201 willbe described referring to FIG. 12. FIG. 12 is a partially enlargedcross-sectional view of the first unit. In manufacturing the vibrationisolation unit 201, first, similarly to the case of the firstembodiment, the first molded body is vulcanizingly molded, and thepartition member 15 is assembled. On the other hand, according to thesecond embodiment, the diaphragm 214 and the stopper rubber member 242are vulcanizingly molded as components separate from each other.

Then, after the partition member 15 is fitted in into the outer tubemember 212 of the first molded body, the annular attaching member 244 isfitted in, and the diaphragm 214 is attached to the upper end side ofthe outer tube member 212 (the small-diameter tube part 12 b). In thiscase, the relative position in the peripheral direction of the annularattaching member 244 with respect to the partition member 15 is set to apredetermined position (that is, similarly to the case of the firstembodiment, the position where the cutout 51 e of the orifice formingpart 51 overlaps with the decompressing-cum-pouring hole 244 c whenviewed in the axis O direction; refer to FIG. 12).

After the diaphragm 214 has been attached to the upper end side of theouter tube member 212, the upper end side of the small-diameter tubepart 12 b of the outer tube member 212 is subjected to diameter reducingwork (caulking work), and the annular attaching member 244 is fixed bycaulking using portion where the diameter of the small-diameter tubepart 12 b has been reduced.

Thus, because the liquid-sealed chamber 16 is formed between thevibration isolation base body 13 and the diaphragm 214, the inside ofthe liquid-sealed chamber 16 is decompressed until a predeterminednegative pressure state is reached by vacuum suction through thedecompressing-cum-pouring hole 244 c, thereafter the liquid is poured inthrough the decompressing-cum-pouring hole 244 c utilizing the negativepressure, and thereby the liquid-sealed chamber 16 is filled with theliquid.

In this case, similarly to the case of the first embodiment, in the stepof vacuum suction of the inside of the liquid-sealed chamber 16 and thestep of filling it with the liquid, suction of the air inside the firstliquid chamber 16A and filling the inside of the first liquid chamber16A with the liquid can be efficiently performed through the orifice 17because the decompressing-cum-pouring hole 244 c is arranged at aposition overlapping with (a position opposing) the cutout 51 e of thepartition member 15 when viewed in the axis O direction.

After completion of filling the liquid-sealed chamber 16 with theliquid, the decompressing-cum-pouring hole 244 c is sealed by the hardball B (sealer) made of an iron and steel material, a resin material andthe like as shown in FIG. 12. The vibration isolation device 210 (thelarge-diameter tube part 12 a of the outer tube member 212) ispressed-in to the pressed-in part 21 of the engine side bracket 20, andthe stopper rubber member 242 is furnished to a predetermined positionof the vibration isolation device 210 and the pressed-in part 21 becausethe vibration isolation device 210 is thereby formed. As a result, afirst unit shown in FIG. 12 (that is, the vibration isolation device 210held by the engine side bracket 20 and furnished with the stopper rubbermember 242) is formed.

After the first unit has been formed, similarly to the case of the firstembodiment, the vibration isolation device 210 is arranged between theopposing surfaces of the bottom surface 31 and the upper surface 33 ofthe vehicle body side bracket 30, and the boss member 11 of thevibration isolation device 210 and the bottom surface 31 of the vehiclebody side bracket 30 are fastened and fixed to each other by the bolt.Thus, manufacturing of the vibration isolation unit 201 is completed(refer to FIG. 9).

The present invention has been described above based on the embodiments;however, it can be easily presumed that the present invention is notlimited to the embodiments described above by any means, and a varietyof improvements and alterations are possible within the scope notdeparting from the objects of the present invention.

The numerical values cited in the respective embodiments are justexamples, and it is a matter of course that other numerical values canbe adopted.

In the first embodiment, a case is described in which the tubular part44 b of the annular attaching member 44 is internally fitted to thesmall-diameter tube part 12 b of the outer tube member 12, ultrasonicwelding is performed from the outer peripheral side of thesmall-diameter tube part 12 b of the outer tube member 12 and therebyboth are welded to each other; however the present invention is notlimited to it, and it may be configured such that the tubular part 44 bof the annular attaching member 44 is externally fitted to thesmall-diameter tube part 12 b of the outer tube member 12, ultrasonicwelding is performed from the outer peripheral side of the tubular part44 b of the annular attaching member 44 and thereby both are welded toeach other. In this case, the decompressing-cum-pouring hole 44 c isarranged only in the annular part 44 a.

In the respective embodiments, a case is described in which the hardball B is used as an example of a sealer that seals thedecompressing-cum-pouring hole 44 c, 244 c; however the presentinvention is not limited to it, and it is a matter of course that othersealers can be adopted. As the other sealers, a rivet can be exemplarilycited. Also, the material of the hard ball B is not limited. Forexample, the hard ball B may be formed of a resin material.

In the respective embodiments, a case is described in which the cutout51 e is positioned right below the decompressing-cum-pouring hole 44 c,244 c of the annular attaching member 44, 244 (overlapped with thedecompressing-cum-pouring hole 44 c, 244 c when viewed in the axis Odirection). In this case, the positional relation of the cutout 51 e andthe decompressing-cum-pouring hole 44 c, 244 c in the respectiveembodiments shows one example, and the imaginary line P passing the axisof the decompressing-cum-pouring hole 44 c, 244 c and extending in thepenetrating direction only has to be positioned at least on the areawhere the cutout 51 e is formed when viewed in the axis O direction.

What is claimed is:
 1. A vibration isolation unit comprising: aliquid-sealed vibration isolation device including a cylindrical outertube member, a boss member positioned on the lower end side of the outertube member, a vibration isolation base body connecting the boss memberand the outer tube member to each other and formed of a rubber-likeelastic body, a diaphragm attached on the upper end side of the outertube member, forming a liquid-sealed chamber between the vibrationisolation base body and the diaphragm and formed of a rubber-likeelastic body, a partition member partitioning the liquid-sealed chamberinto a first liquid chamber on the vibration isolation base body sideand a second liquid chamber on the diaphragm side, and an orificeallowing the first liquid chamber and the second liquid chamber tocommunicate with each other; an engine side bracket including apressed-in part to which the outer tube member of the liquid-sealedvibration isolation device is pressed-in and which is connected to theengine side; a vehicle body side bracket including a bottom surface towhich the boss member of the liquid-sealed vibration isolation device isfixed, a pair of side walls erected from the bottom surface and opposingto each other embracing the liquid-sealed vibration isolation device,and an upper surface connecting the pair of side walls to each other andopposing the bottom surface embracing the liquid-sealed vibrationisolation device, and connected to a vehicle body side; and a stopperrubber member interposed between the side wall of the vehicle body sidebracket and the pressed-in part of the engine side bracket and formed ofa rubber-like elastic body; wherein the stopper rubber member includesstopper rubber upper surfaces of which one side continues to an outeredge of the diaphragm and which are disposed on the upper end side ofthe pressed-in part of the engine side bracket, and stopper rubber sidewalls hung down from the other side of the stopper rubber upper surfacesand disposed between the side walls of the vehicle body side bracket andthe pressed-in part of the engine side bracket.
 2. The vibrationisolation unit according to claim 1 further comprising: an annularattaching member to which the diaphragm is vulcanizingly adhered andwhich is formed of a resin material into an annular shape when viewed inthe axial direction; wherein the outer tube member is formed of a resinmaterial into a cylindrical shape, and the diaphragm is attached to theupper end side of the outer tube member by that the annular attachingmember is welded to the outer tube member by ultrasonic welding.
 3. Thevibration isolation unit according to claim 2, wherein the annularattaching member includes an annular part to which the diaphragm isvulcanizingly adhered and a tubular part connected to the lower surfaceside of the annular part, formed into a cylindrical shape, andinternally fitted to the inner peripheral side or externally fitted tothe outer peripheral side of the outer tube member, and the outer tubemember and the tubular part of the annular attaching member are weldedto each other by subjecting the outer peripheral side of the outer tubemember to which the tubular part of the annular attaching member isinternally fitted on the inner peripheral side or the outer peripheralside of the tubular part of the annular attaching member externallyfitted to the outer peripheral side of the outer tube member toultrasonic welding.
 4. The vibration isolation unit according to claim3, wherein the outer tube member includes a large-diameter tube partpositioned on the lower end side and a small-diameter tube part formedto have a diameter smaller than that of the large-diameter tube part andpositioned on the upper side, with the large-diameter tube partpressed-in to the pressed-in part of the engine side bracket, and thetubular part of the annular attaching member is internally fitted to theinner peripheral side of the small-diameter tube part of the outer tubemember.
 5. The vibration isolation unit according to claim 4, wherein,in the annular attaching member, an outer edge portion of the annularpart is formed so as to extend outward in the radial direction from thetubular part, and the lower surface of the outer edge portion of theannular part formed so as to extend outward in the radial direction fromthe tubular part is made to abut on an upper end surface of thesmall-diameter tube part of the outer tube member.
 6. The vibrationisolation unit according to claim 1, wherein the liquid-sealed vibrationisolation device includes a decompressing-cum-pouring hole allowing theliquid-sealed chamber to communicate with the outside and a sealersealing the decompressing-cum-pouring hole, and is manufactured byfilling the liquid-sealed chamber with liquid by pouring the liquidthrough the decompressing-cum-pouring hole after decompressing inside ofthe liquid-sealed chamber through the decompressing-cum-pouring hole,and sealing the decompressing-cum-pouring hole by the sealer, and thedecompressing-cum-pouring hole is disposed in the annular attachingmember.